Drink driving

Friday 28th August 2015

Having previously said I don't drink, I'm going to see how drunk I can get and still be under the UK alcohol limit. I decided it was a teeny bit unethical to get behind the wheel, so I'm going to test myself on GTA V instead.

I created a simple course that mimics my everyday life. So I'm going to drive from my luxury penthouse apartment to the clothes shop for a new dress, then go for a haircut before driving to the golf course.

But first, Science™. Or if science isn't your thing, just skip to the heading marked Sober.

Blood alcohol concentration

When a bottle says that it's 5% or 40% alcohol, that's the amount of the liquid in the bottle which is pure ethanol, the stuff that gets you drunk. So a pint (568mL) of Carlsberg Export at 5% is 28.4mL of ethanol (568 * 5 / 100).

In the UK we use a system called units to make it easier to keep track of what you've drunk. One unit is 10mL of ethanol. So a pint of Carlsberg Export is 2.84 units (28.4 / 10), although it just says 2.8 on the can to avoid confusing drunk people.

Still with me?

Drink drive limits are expressed as the amount of ethanol in a certain amount of blood, or breath. The UK drink drive limit is currently 80mg of ethanol per 100mL of blood (or 35 μg per 100mL of breath). 80mg/100mL is more commonly expressed as 0.08 BAC (Blood Alcohol Concentration).

But how much do I need to drink to stay below that?

The Widmark method

The generally accepted method for calculating blood alcohol is the Widmark method, which is gives the blood alcohol concentration in g%:

The gender constant is 0.68 for men and 0.55 for women and relates to the different amounts of water in the bodies of men and women. Re-arranging this to give me the most I can drink and still be below the UK drink drive limit gives me a wonderfully simple formula:

Ethanol in mL = weight in Kg * gender constant

For me, this is 47.6mL ethanol, which is 4.76 UK units. This is just over a pint and half of Export, or four shots of gin, which is what I'm going to drink.

I know before I even open the bottle that I'm going to be utterly incapable of driving anywhere.

Sober

First, I need a benchmark, so I drove the course sober in 5 minutes and 39 seconds.

Drunk in the game

If you've played GTA V, you'll know that there are all sorts of ways to get high in the game. As an extra benchmark I wanted to get plastered in the game (still sober in real life) and then drive the same course to see what time I get. The vehicle swerves all over the road after you've had a few and is very hard to control.

The main problem here is that you can't shop or get a haircut while the police are after you, and drink-driving catches their attention pretty quickly.

It didn't end well and no matter how many times I tried, I couldn't get to the golf club without dying. Here's an example.

Drunk in real life

To be honest I wasn't looking forward to this, it's definitely one of the worse ideas I've had lately. But here goes.

I drank four shots of gin and a pint of tonic water in ten minutes and then tried to play the game. I got round the course in 7 minutes 12 seconds, but I found it hard to navigate the menus and failed to buy a dress or get a haircut.

There's no way I should be driving in real life. My driving wasn't that bad, I could control the car much easier than being drunk in the game, but I found it very hard to concentrate on playing and keeping the truck on the road. I guess this is why we have drink-drive laws! Apologies for the mumbly, slurred commentary in the video.